EUV light source and apparatus for lithography

ABSTRACT

An extreme ultra violet (EUV) radiation source apparatus includes a collector, a target droplet generator for generating a tin (Sn) droplet, a rotatable debris collection device and a chamber enclosing at least the collector and the rotatable debris collection device. The rotatable debris collection device includes a first end support, a second end support and a plurality of vanes, ends of which are supported by the first end support and the second end support, respectively. A surface of at least one of the plurality of vanes is coated by a catalytic layer, which reduces a SnH 4  to Sn.

This application claims priority of Provisional Application No.62/525,570 filed on Jun. 27, 2017, the entire contents of which areincorporated herein by reference.

TECHNICAL FIELD

This disclosure relates to pattern forming methods used in semiconductormanufacturing processes, and an apparatus for lithography.

BACKGROUND

The semiconductor integrated circuit (IC) industry has experiencedexponential growth. Technological advances in IC materials and designhave produced generations of ICs where each generation has smaller andmore complex circuits than the previous generation. In the course of ICevolution, functional density (i.e., the number of interconnecteddevices per chip area) has generally increased while geometry size(i.e., the smallest component (or line) that can be created using afabrication process) has decreased. This scaling down process generallyprovides benefits by increasing production efficiency and loweringassociated costs. Such scaling down has also increased the complexity ofprocessing and manufacturing ICs.

For example, the need to perform higher resolution lithography processesgrows. One lithography technique is extreme ultraviolet lithography(EUVL). The EUVL employs scanners using light in the extreme ultraviolet(EUV) region, having a wavelength of about 1-100 nm. Some EUV scannersprovide 4×reduction projection printing, similar to some opticalscanners, except that the EUV scanners use reflective rather thanrefractive optics, i.e., mirrors instead of lenses. One type of EUVlight source is laser-produced plasma (LPP). LPP technology produces EUVlight by focusing a high-power laser beam onto small tin droplet targetsto form highly ionized plasma that emits EUV radiation with a peakmaximum emission at 13.5 nm. The EUV light is then collected by a LPPcollector and reflected by optics towards a lithography target, e.g., awafer. The LPP collector is subjected to damage and degradation due tothe impact of particles, ions, radiation, and most seriously, tindeposition.

BRIEF DESCRIPTION OF THE DRAWINGS

The present disclosure is best understood from the following detaileddescription when read with the accompanying figures. It is emphasizedthat, in accordance with the standard practice in the industry, variousfeatures are not drawn to scale and are used for illustration purposesonly. In fact, the dimensions of the various features may be arbitrarilyincreased or reduced for clarity of discussion.

FIG. 1 is a schematic view of an EUV lithography system with a laserproduced plasma (LPP) EUV radiation source, constructed in accordancewith some embodiments of the present disclosure.

FIG. 2A is a schematic front view of a debris collection mechanism usedin the EUV radiation source according to some embodiments of the presentdisclosure. FIG. 2B is a schematic side view of a debris collectionmechanism used in the EUV radiation source according to some embodimentsof the present disclosure. FIG. 2C is a partial picture of a vane usedin the EUV radiation source according to some embodiments of the presentdisclosure.

FIGS. 3A and 3B illustrate schematic cross sectional views of a vanewith a catalytic layer according to some embodiments of the presentdisclosure.

FIGS. 4A-4D illustrate various surface textures of the vane according tosome embodiments of the present disclosure.

DETAILED DESCRIPTION

The following disclosure provides many different embodiments, orexamples, for implementing different features of the provided subjectmatter. Specific examples of components and arrangements are describedbelow to simplify the present disclosure. These are, of course, merelyexamples and are not intended to be limiting. For example, the formationof a first feature over or on a second feature in the description thatfollows may include embodiments in which the first and second featuresare formed in direct contact, and may also include embodiments in whichadditional features may be formed between the first and second features,such that the first and second features may not be in direct contact. Inaddition, the present disclosure may repeat reference numerals and/orletters in the various examples. This repetition is for the purpose ofsimplicity and clarity and does not in itself dictate a relationshipbetween the various embodiments and/or configurations discussed.

Further, spatially relative terms, such as “beneath,” “below,” “lower,”“above,” “upper” and the like, may be used herein for ease ofdescription to describe one element or feature's relationship to anotherelement(s) or feature(s) as illustrated in the figures. The spatiallyrelative terms are intended to encompass different orientations of thedevice in use or operation in addition to the orientation depicted inthe figures. The apparatus/device may be otherwise oriented (rotated 90degrees or at other orientations) and the spatially relative descriptorsused herein may likewise be interpreted accordingly. In addition, theterm “made of” may mean either “comprising” or “consisting of.”

The present disclosure is generally related to extreme ultraviolet (EUV)lithography system and methods. More particularly, it is related toapparatus and methods for mitigating contamination on a collector in alaser produced plasma (LPP) EUV radiation source. The collector, alsoreferred to as an LPP collector or an EUV collector, is an importantcomponent of the LPP EUV radiation source. It collects and reflects EUVradiation and contributes to overall EUV conversion efficiency. However,it is subjected to damages and degradations due to the impact ofparticles, ions, radiation, and debris deposition. In particular, a tin(Sn) debris is one of the contamination sources to the EUV collector.One of the objectives of the present disclosure is directed to reducingdebris deposition onto the LPP collector thereby increasing its usablelifetime.

FIG. 1 is a schematic and diagrammatic view of an EUV lithographysystem. The EUV lithography system includes an EUV radiation sourceapparatus 100 to generate EUV light, an exposure tool 200, such as ascanner, and an excitation laser source apparatus 300. As shown in FIG.1, in some embodiments, the EUV radiation source apparatus 100 and theexposure tool 200 are installed on a main floor MF of a clean room,while the excitation source apparatus 300 is installed in a base floorBF located under the main floor. Each of the EUV radiation sourceapparatus 100 and the exposure tool 200 are placed over pedestal platesPP1 and PP2 via dampers DP1 and DP2, respectively. The EUV radiationsource apparatus 100 and the exposure tool 200 are coupled to each otherby a coupling mechanism, which may include a focusing unit.

The lithography system is an extreme ultraviolet (EUV) lithographysystem designed to expose a resist layer by EUV light (or EUVradiation). The resist layer is a material sensitive to the EUV light.The EUV lithography system employs the EUV radiation source apparatus100 to generate EUV light, such as EUV light having a wavelength rangingbetween about 1 nm and about 100 nm. In one particular example, the EUVradiation source 100 generates an EUV light with a wavelength centeredat about 13.5 nm. In the present embodiment, the EUV radiation source100 utilizes a mechanism of laser-produced plasma (LPP) to generate theEUV radiation.

The exposure tool 200 includes various reflective optic components, suchas convex/concave/flat mirrors, a mask holding mechanism including amask stage, and wafer holding mechanism. The EUV radiation EUV generatedby the EUV radiation source 100 is guided by the reflective opticalcomponents onto a mask secured on the mask stage. In some embodiments,the mask stage includes an electrostatic chuck (e-chuck) to secure themask. Because gas molecules absorb EUV light, the lithography system forthe EUV lithography patterning is maintained in a vacuum or a-lowpressure environment to avoid EUV intensity loss.

In the present disclosure, the terms mask, photomask, and reticle areused interchangeably. In the present embodiment, the mask is areflective mask. One exemplary structure of the mask includes asubstrate with a suitable material, such as a low thermal expansionmaterial or fused quartz. In various examples, the material includesTiO₂ doped SiO₂, or other suitable materials with low thermal expansion.The mask includes multiple reflective multiple layers (ML) deposited onthe substrate. The ML includes a plurality of film pairs, such asmolybdenum-silicon (Mo/Si) film pairs (e.g., a layer of molybdenum aboveor below a layer of silicon in each film pair). Alternatively, the MLmay include molybdenum-beryllium (Mo/Be) film pairs, or other suitablematerials that are configurable to highly reflect the EUV light. Themask may further include a capping layer, such as ruthenium (Ru),disposed on the ML for protection. The mask further includes anabsorption layer, such as a tantalum boron nitride (TaBN) layer,deposited over the ML. The absorption layer is patterned to define alayer of an integrated circuit (IC). Alternatively, another reflectivelayer may be deposited over the ML and is patterned to define a layer ofan integrated circuit, thereby forming an EUV phase shift mask.

The exposure tool 200 includes a projection optics module for imagingthe pattern of the mask on to a semiconductor substrate with a resistcoated thereon secured on a substrate stage of the exposure tool 200.The projection optics module generally includes reflective optics. TheEUV radiation (EUV light) directed from the mask, carrying the image ofthe pattern defined on the mask, is collected by the projection opticsmodule, thereby forming an image onto the resist.

In the present embodiments, the semiconductor substrate is asemiconductor wafer, such as a silicon wafer or other type of wafer tobe patterned. The semiconductor substrate is coated with a resist layersensitive to the EUV light in the present embodiment. Various componentsincluding those described above are integrated together and are operableto perform lithography exposing processes.

The lithography system may further include other modules or beintegrated with (or be coupled with) other modules.

As shown in FIG. 1, the EUV radiation source 100 includes a targetdroplet generator 115 and a LPP collector 110, enclosed by a chamber105. The target droplet generator 115 generates a plurality of targetdroplets DP. In some embodiments, the target droplets DP are tin (Sn)droplets. In some embodiments, the tin droplets each have a diameterabout 30 microns (μm). In some embodiments, the tin droplets DP aregenerated at a rate about 50 droplets per second and are introduced intoa zone of excitation ZE at a speed about 70 meters per second (m/s).Other material can also be used for the target droplets, for example, atin containing liquid material such as eutectic alloy containing tin orlithium (Li).

The excitation laser LR2 generated by the excitation laser sourceapparatus 300 is a pulse laser. In some embodiments, the excitationlayer includes a pre-heat laser and a main laser. The pre-heat laserpulse is used to heat (or pre-heat) the target droplet to create alow-density target plume, which is subsequently heated (or reheated) bythe main laser pulse, generating increased emission of EUV light.

In various embodiments, the pre-heat laser pulses have a spot size about100 μm or less, and the main laser pulses have a spot size about 200-300μm.

The laser pulses LR2 are generated by the excitation laser source 300.The laser source 300 may include a laser generator 310, laser guideoptics 320 and a focusing apparatus 330. In some embodiments, the lasersource 310 includes a carbon dioxide (CO₂) or a neodymium-doped yttriumaluminum garnet (Nd:YAG) laser source. The laser light LR1 generated bythe laser generator 300 is guided by the laser guide optics 320 andfocused into the excitation laser LR2 by the focusing apparatus 330, andthen introduced into the EUV radiation source 100.

The laser light LR2 is directed through windows (or lenses) into thezone of excitation ZE. The windows adopt a suitable materialsubstantially transparent to the laser beams. The generation of thepulse lasers is synchronized with the generation of the target droplets.As the target droplets move through the excitation zone, the pre-pulsesheat the target droplets and transform them into low-density targetplumes. A delay between the pre-pulse and the main pulse is controlledto allow the target plume to form and to expand to an optimal size andgeometry. When the main pulse heats the target plume, a high-temperatureplasma is generated. The plasma emits EUV radiation EUV, which iscollected by the collector mirror 110. The collector 110 furtherreflects and focuses the EUV radiation for the lithography exposingprocesses. In some embodiments, a droplet catcher 120 is installedopposite the target droplet generator 115. The droplet catcher 120 isused for catching excessive target droplets. For example, some targetdroplets may be purposely missed by the laser pulses.

The collector 110 is designed with a proper coating material and shapeto function as a mirror for EUV collection, reflection, and focusing. Insome embodiments, the collector 110 is designed to have an ellipsoidalgeometry. In some embodiments, the coating material of the collector 100is similar to the reflective multilayer of the EUV mask. In someexamples, the coating material of the collector 110 includes a ML (suchas a plurality of Mo/Si film pairs) and may further include a cappinglayer (such as Ru) coated on the ML to substantially reflect the EUVlight. In some embodiments, the collector 110 may further include agrating structure designed to effectively scatter the laser beamdirected onto the collector 110. For example, a silicon nitride layer iscoated on the collector 110 and is patterned to have a grating pattern.

In such an EUV radiation source apparatus, the plasma caused by thelaser application creates physical debris, such as ions, gases and atomsof the droplet, as well as the desired EUV radiation. It is necessary toprevent the accumulation of material on the collector 110 and also toprevent physical debris exiting the chamber 105 and entering theexposure tool 200.

As shown in FIG. 1, in the present embodiments, a buffer gas is suppliedfrom a first buffer gas supply 130 through the aperture in collector 110by which the pulse laser is delivered to the tin droplets. In someembodiments, the buffer gas is H₂, He, Ar, N or another inert gas. Incertain embodiments, H₂ is used as H radicals generated by ionization ofthe buffer gas can be used for cleaning purposes. The buffer gas canalso be provided through one or more second buffer gas supplies 135toward the collector 110 and/or around the edges of the collector 110.Further, the chamber 105 includes one or more gas outlets 140 so thatthe buffer gas is exhausted outside the chamber 105.

Hydrogen gas has low absorption to the EUV radiation. Hydrogen gasreaching to the coating surface of the collector 110 reacts chemicallywith a metal of the droplet forming a hydride, e.g., metal hydride. Whentin (Sn) is used as the droplet, stannane (SnH₄), which is a gaseousbyproduct of the EUV generation process, is formed. The gaseous SnH₄ isthen pumped out through the outlet 140. However, it is difficult toexhaust all gaseous SnH₄ from the chamber and to prevent the SnH₄ fromentering the exposure tool 200.

To trap the SnH₄ or other debris, one or more debris collectionmechanisms (DCM) 150 are employed in the chamber 105.

As shown in FIG. 1, one or more DCMs 150 are disposed along optical axisA1 between the zone of excitation ZE and an output port 160 of the EUVradiation source 100. FIG. 2A is a front view of the DCM 150 and FIG. 2Bis a schematic side view of DCM 150. FIG. 2C is a partial picture of theDCM 150. The DCM 150 includes a frustoconical support frame 151, a firstend support 153 and a second end support 154 that operably support aplurality of vanes 152 that rotate within the housings. The first endsupport 153 has a larger diameter than the second end support 154. TheDCM 150 serves to prevent the surface of collector 110 and/or otherelements/portions of the inside the chamber 105 from being coated by Snvapor by sweeping out slow Sn atoms and/or SnH₄ via rotating vanes 152.

The plurality of vanes 152 project radially inwardly from thefrustoconical support frame 151. The vanes 152 are thin and elongateplates. In some embodiments, each of the vanes has a triangular ortrapezoid or trapezium shape in plan view. The vanes 152 are aligned sothat their longitudinal axes are parallel to the optical axis A1 so thatthey present the smallest possible cross-sectional area to the EUVradiation EUV. The vanes 152 project towards the optical axis A1, but donot extend as far as the optical axis. In some embodiments, a centralcore of the DCM 150 is empty. The DCM 150 is driven to rotate by a driveunit including one or more motors, one or more belts and/or one or moregears, or any rotating mechanism. The vanes 152 are heated at 100° C. to400° C. by a heater in some embodiments.

The DCM 150 is made of suitable material such as stainless steel, Cu, Alor ceramics. In certain embodiments, the DCM 150 is made of stainlesssteel. In the present embodiments, the surface of the DCM 150, inparticular the surface of vanes 152, is coated with a catalytic material158 that can reduce SiH₄ to Sn, as shown in FIG. 3A. The catalyticmaterial includes ruthenium (Ru), tin (Sn), tin oxide, titanium oxide,or any combination thereof. In some embodiments, Ru is used. The Rucoated surface of the DCM 150 reduces SiH₄ to Sn, and traps Sn thereon.

Ruthenium may be coated on the surface of the vanes by a thermaldeposition method, an e-beam deposition method or any other suitablefilm formation methods. The thickness of the Ru layer is in a range fromabout 2 nm to about 50 nm in some embodiments. Similar methods andconfigurations may be applied to catalytic layers comprising anothermaterial.

Further, in some embodiments of the present disclosure, the surface ofvanes 152 has a roughened structure as shown in FIG. 3B, and thecatalytic layer 158 is formed on the roughened surface. The roughenedsurface has nano-scale microstructures which are regularly and/orirregularly/randomly arranged.

In some embodiments, as shown in FIG. 4A, the surface of vanes 152 hasregularly formed depressions or holes, each of which size (e.g., adiameter or a largest width) is in a range from about 10 nm to about 500nm. The depth of the depressions or holes is in a range from about 50 nmto about 1000 nm in some embodiments. The depressions or holes are twodimensionally arranged with a pitch of about 20 nm to about 1000 nm insome embodiments. The shape of the opening of the depressions or holesmay be circular, ellipsoid or polygonal.

In other embodiments, as shown in FIG. 4B, the surface of vanes 152 hasregularly formed protrusions, each of which size (e.g., a diameter or alargest width) is in a range from about 10 nm to about 500 nm. Theheight of the protrusions is in a range from about 50 nm to about 1000nm in some embodiments. The protrusions are two-dimensionally arrangedwith a pitch of about 20 nm to about 1000 nm in some embodiments. Thetop shape of the protrusions may be circular, ellipsoid or polygonal.The protrusions may have a columnar, a pyramidal or conical shape.

The regular nano-structure shown in FIGS. 4A and 4B can be formed bysuitable patterning operations including lithography and etchingoperations. The nano-structures may be formed by nano-printingtechnologies.

In some embodiments, the surface of vanes 152 has irregularly formednano-structures. As shown in FIG. 4C, the surface of vanes 152 hasirregularly formed protrusions, each of which diameter is in a rangefrom about 5 nm to about 500 nm. The height of the protrusions is in arange from about 50 nm to about 1000 nm in some embodiments. Theprotrusions may have a columnar, a pyramidal or conical shape. Theirregular nano-structures may be formed by a sand blast method, a wetetching method using an acid or alkaline solution, an ion bombardmentmethod or a plasma etching method. The arithmetic average surfaceroughness Ra of the roughened surface is in a range from about 10 nm toabout 500 nm in some embodiments, and in in a range from about 50 nm toabout 200 nm in other embodiments.

In certain embodiments, the surface of vanes 152 has a porous structure.As shown in FIG. 4D, the surface of vanes 152 has a porous structure,and each of the pores has a size in a range from about 5 nm to about 500nm. The porous structures may be formed by a sand blast method, a wetetching method using an acid or alkaline solution, an ion bombardmentmethod or a plasma etching method. The surface roughness Ra of theroughened surface is in a range from about 10 nm to about 500 nm in someembodiments, and in in a range from about 50 nm to about 200 nm in otherembodiments.

In the foregoing embodiments, the surfaces of the vanes 152 are directlyformed to have nano-structures, and then the catalytic layer is formedon the roughened surface. In other embodiments, one or more additionallayers having nano-structures is formed on the surface of the vanes andthen the catalytic layer is formed on the one or more additional layers.

In some embodiments, the nano-scale roughened surface can be formed by,for example, depositing nano-scale particles using a thermal depositionmethod, a physical vapor deposition method, a chemical vapor depositionmethod and/or a coating method. In other embodiments, a wet treatment ora thermal treatment is performed on the surface of the vanes to form thenano-scale roughened surface. In certain embodiments, the vanes includetwo or more layers and the layer disposed at the surface of the vanesare vaporized or sublimated, thereby forming nano-scale roughenedsurface. In some embodiments, a sand blasting method is performed toform the nano-scale roughened surface.

By making the surface of vanes 152 nano-scale-roughened surface, it ispossible to enlarge a surface area of the catalytic layer 158 and thusit is possible to enhance the reduction efficiency of SnH₄ at thesurface of vanes.

In the foregoing embodiments, a catalytic layer is made of a material,such as Ru, to reduce SnH₄ to Sn. When the droplet used to generate EUVradiation is made of a different material than Sn, the same as ordifferent catalytic material can be used as the a catalytic materiallayer 158.

It will be understood that not all advantages have been necessarilydiscussed herein, no particular advantage is required for allembodiments or examples, and other embodiments or examples may offerdifferent advantages.

In the present disclosure, by applying a catalytic layer made of, forexample, Ru, on the surface of vanes in the debris collection mechanism(DCM), it is possible to reduce SnH₄ vapor to metal Sn, and thus it ispossible to prevent contamination of Sn debris on the collector.Therefore, it is possible to extend a life of the collector in the EUVradiation source for a EUV lithography system.

According to one aspect of the present disclosure, a debris collectiondevice for an extreme ultra violet (EUV) radiation source apparatusincludes a first end support, a second end support and a plurality ofvanes, ends of which are supported by the first end support and thesecond end support, respectively. A surface of at least one of theplurality of vanes is coated by a catalytic layer, which reduces ahydride.

According to another aspect of the present disclosure, an extreme ultraviolet (EUV) radiation source apparatus includes a collector, a targetdroplet generator for generating a tin (Sn) droplet, a rotatable debriscollection device and a chamber enclosing at least the collector and therotatable debris collection device. The rotatable debris collectiondevice includes a first end support, a second end support and aplurality of vanes, ends of which are supported by the first end supportand the second end support, respectively. A surface of at least one ofthe plurality of vanes is coated by a catalytic layer, which reducesSnH₄ to Sn.

According to yet another aspect of the present disclosure, in a methodfor generating an extreme ultra violet (EUV) radiation, a tin droplet isirradiated with laser light in a hydrogen gas ambient, thereby creatingthe EUV radiation. SnH₄ is reduced by using a debris collection deviceto Sn, thereby collecting debris. The debris collection device includesa plurality of vanes, opposing ends of which are supported by a firstend support and a second end support, respectively, and a surface of atleast one of the plurality of vanes is coated with a Ru layer.

The foregoing outlines features of several embodiments or examples sothat those skilled in the art may better understand the aspects of thepresent disclosure. Those skilled in the art should appreciate that theymay readily use the present disclosure as a basis for designing ormodifying other processes and structures for carrying out the samepurposes and/or achieving the same advantages of the embodiments orexamples introduced herein. Those skilled in the art should also realizethat such equivalent constructions do not depart from the spirit andscope of the present disclosure, and that they may make various changes,substitutions, and alterations herein without departing from the spiritand scope of the present disclosure.

What is claimed is:
 1. An extreme ultra violet (EUV) radiation sourceapparatus, comprising: a collector; a target droplet generator forgenerating a tin (Sn) droplet; a rotatable debris collection device; anda chamber enclosing at least the collector and the rotatable debriscollection device, wherein: the rotatable debris collection deviceincludes: a first end support; a second end support; and a plurality ofvanes, ends of which are supported by the first end support and thesecond end support, respectively, a surface of at least one of theplurality of vanes is coated by a catalytic layer, which reduces SnH₄ toSn, the surface includes a roughened surface having regularly formedstructures, the regularly formed structures including depressions orholes that are two dimensionally arranged with a depth of from 50 nm to1000 nm, and the catalytic layer includes titanium oxide and Ru disposedon the at least one of the plurality of vanes.
 2. The EUV radiationsource apparatus of claim 1, further comprising: a gas inlet; and a gasoutlet, wherein: a hydrogen gas is supplied from the gas inlet, and thedebris collection device transfers a gas toward the outlet by a rotatingoperation.
 3. The EUV radiation source apparatus of claim 1, wherein:the catalytic layer is coated on the roughened surface.
 4. The EUVradiation source apparatus of claim 1, wherein: a size of each of theregularly formed structures is in a range from 10 nm to 500 nm.
 5. TheEUV radiation source apparatus of claim 1, further comprising: a laserlight source for supplying laser light; and one or more opticalcomponents, wherein the Sn droplet generated by the target dropletgenerator is irradiated by the laser.
 6. The EUV radiation sourceapparatus of claim 1, wherein the catalytic layer further includes atleast one of a tin (Sn) layer and a tin oxide layer.
 7. The EUVradiation source apparatus of claim 1, wherein one or more layers isdisposed between the surface and the catalytic layer.
 8. The EUVradiation source apparatus of claim 1, wherein the roughened surface isformed by depositing particles by a method selected from the groupconsisting of a thermal deposition, a physical vapor deposition,chemical vapor deposition, and a coating.
 9. The EUV radiation sourceapparatus of claim 1, wherein the roughened surface is formed by atleast one method of a wet treatment and a thermal treatment.
 10. The EUVradiation source apparatus of claim 1, wherein the one or more layersare disposed on the surface by at least one method of a vaporization anda sublimation.
 11. The EUV radiation source apparatus of claim 1,wherein the depressions or the holes are two dimensionally arranged witha pitch of 20 nm to 1000 nm.
 12. An extreme ultra violet (EUV) radiationsource apparatus, comprising: a collector; a target droplet generatorfor generating a tin (Sn) droplet; a rotatable debris collection device;and a chamber enclosing at least the collector and the rotatable debriscollection device, wherein: the rotatable debris collection deviceincludes: a first end support; a second end support; and a plurality ofvanes, ends of which are supported by the first end support and thesecond end support, respectively, a surface of at least one of theplurality of vanes is coated by a catalytic layer, which reduces SnH₄ toSn, the surface includes a roughened surface having irregularly formedstructures, the irregularly formed structures having an arithmeticaverage surface roughness Ra of the roughened surface in a range from 10nm to 500 nm, and comprising depressions or holes that are twodimensionally arranged with a depth of from 50 nm to 1000 nm, and thecatalytic layer includes titanium oxide and Ru disposed on the at leastone of the plurality of vanes.
 13. An extreme ultra violet (EUV)radiation source apparatus, comprising: a collector; a target dropletgenerator for generating a tin (Sn) droplet; a rotatable debriscollection device; and a chamber enclosing at least the collector andthe rotatable debris collection device, wherein the rotatable debriscollection device includes a plurality of vanes, and a surface of atleast one of the plurality of vanes is coated by a catalytic layer, thecatalytic layer including titanium oxide and Ru disposed on the at leastone of the plurality of vanes, which reduces SnH₄ to Sn.
 14. The EUVradiation source apparatus of claim 13, wherein the catalytic layerfurther includes at least one of tin (Sn) and a tin oxide.
 15. The EUVradiation source apparatus of claim 13, wherein the catalytic layer isformed on a roughened surface and a roughness Ra of the roughenedsurface is in a range from 10 nm to 500 nm.
 16. The EUV radiation sourceapparatus of claim 15, wherein the roughened surface includesprotrusions, and a top shape of the protrusions is at least one ofcircular, ellipsoid and polygonal.
 17. The EUV radiation sourceapparatus of claim 15, wherein the roughened surface includes porousstructures formed by at least one of a sand blast method, a wet etchingmethod using an acid or alkaline solution, an ion bombardment method anda plasma etching method.
 18. The EUV radiation source apparatus of claim13, wherein the surface includes a roughened surface having irregularlyformed structures comprising depressions or holes that are twodimensionally arranged with a depth of from 50 nm to 1000 nm.